The new adaptive energy saver mode will automatically kick in or back off depending on what your laptop is actually doing, rather than just reacting to how much battery is left.

This makes it a little different from the existing energy saver mode that usually just dulls the display by 30 per cent, kills off background apps, halts non-critical Windows updates, and pauses syncing for bits like OneDrive, OneNote, and Phone Link.

This adaptive version will behave differently. It won’t mess with screen brightness at all, making it far less obvious when it’s working its magic on laptops, tablets, and handhelds.

Microsoft’s Windows Insider team explained: “Adaptive energy saver is an opt-in feature that automatically enables and disables energy saver, without changing screen brightness, based on the power state of the device and the current system load,”  It’s now rolling out to the Canary Channel for testing, with a wider release expected later this year.

You won’t get this feature on desktop PCs, but no one is going to need it. Besides Vole brought the basic energy saver mode to all Windows machines last year, so even tower users can shave a bit off their electricity bill. This new tweak is aimed at battery-powered kit that actually needs it.